World records in endurance sports are not accomplished at age 55. This is because one of the unavoidable consequences of aging is a decline in the maximal capacity of the cardiovascular system to pump blood and deliver oxygen while removing metabolic waste products. The components of the cardiovascular pump performance are 1) the maximal heart rate that can be achieved, 2) the size and contractility of the heart muscle, and 3) the compliance (stiffness) of the arterial tree. It is known that aging affects each of these three variables.
Young children generally have a maximal heart rate that approaches 220 beats per minute. This maximal rate falls throughout life. By age 60, maximal heart rate in a group of 100 men will average about 160 beats per minute. This fall in heart rate seems to be a linear process so that maximal heart rate can be estimated by the formula: Max heart rate=220−age. This is an estimate, however. If the maximal heart rates of those same 100 men are measured during a maximal heart rate test, there would probably be a range of heart rates between 140 and 180 beats per minute.
There is no strong evidence to suggest that training influences the decline in maximal heart rate. The blood pumped out of the heart enters the systemic arterial system. For the youth, this system of arteries is quite flexible or compliant. This is important for the performance of the heart. Compliant vessel walls stretch when blood is pumped through them, lowering the resistance that the heart must overcome to eject it volume of each beat. As we age, these vessels loose their elasticity. Consequently, resting blood pressure and blood pressure during exercise slowly increase as we age. Continued training appears to reduce this aging effect, but does not eliminate it. Increased peripheral resistance results in a decrease in maximal blood flow to working muscles. However, at sub maximal exercise intensities, the 10%-15% decrease in blood flow is compensated for by the increase in oxygen extraction. This compensation is probably possible due to the increased transit time of the blood through the capillary tree.
In the sedentary population, cardiovascular performance declines progressively. Much of this decline is due to 1) physical inactivity and 2) increased body weight (fat). Maximal oxygen consumption declines about 10% per decade after age 25. However, if body composition is maintained and physical activity levels are kept constant, the decline in maximum oxygen uptake (VO2 Max) due to aging is only about 5% per decade. Prior to age 50, this decline may even be less, perhaps on 1%-2% per decade in hard training master athletes. Ultimately, cardiovascular capacity is reduced, however, due to the unavoidable decline in maximal heart rate.
Currently in America approximately one in three or 58 million American Adults aged 20 through 74 are overweight. This is true even though more is now known than ever before about the harmful effects of being overweight and in poor physical condition. Every year as society is becoming more automated many manual labor jobs are being replaced by machines. There is less physical labor Americans must do. Also, for most people large amounts of food are easy to find and afford.
Some people are able to successfully start and stay with a healthy exercise program that involves weight lifting and cardiovascular exercise. Many of these people join gyms to have access to expensive machines designed to help them exercise. However, many people find it difficult and expensive to exercise at a gym. There are also additional problems with gyms at a fitness studio and/or home gyms. For example, conventional design fitness machines are generally in fixed locations in a fitness studio or at the user's residence. Fitness machines typically provide only one direction of motion for training. Also, with fitness machines each individual muscle group (agonist) is trained individually, that is, without stressing its opposing muscle group (antagonist) with reversed movement sequences. In the prior art there are a few stationary machines that train only a small number of muscle groups. Hence, in order to train a large number of muscle groups, prior art fitness machines require high mechanical and equipment expense for multiple machines.
With all the problems associated with prior art stationary gym equipment, some people decide to start walking or running for exercise. These exercises are good for cardiovascular exercise but they are not as effective as resistance training for muscular exercise and development.
What is needed is a personal exercise device that combines cardiovascular training and resistance training.